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Oxidative Phosphorylation and Electron Transport Chain I
Electron Transport Chain II
Electron Transport Chain III
ATP Synthase I
ATP Synthase II
100
Oxidative phosphorylation is the oxygen-dependent phosphorylation of ADP to form ATP. What are the three energy-conversion processes in the membrane?
1. Movement of electrons down the electron electron transport chain from NADH to oxygen 2. Coupled transport of protons across the inner mitochondrial membrane to form a proton gradient. 3. Use of the proton gradient to drive ATP synthesis by the ATP synthase
100
Which complex catalyzes the overall reaction NADH + ubiquinone (oxidized) --> NAD+ + ubiquinone (reduced)
Complex I
100
Which complex transfers electrons from FADH2 to complex III?
Complex II
100
F1 synthesizes ATP at three sites formed at each what?
a/b subunit pair
100
What are the three conformational states?
Open, Loose, Tight
200
What feeds electrons into the electron transport chain?
NADH from the TCA Cycle and glycolysis
200
Fill in the blanks about Complex I of the electron transport chain. Complex I has several different electron carriers associated with it. _____(a)_____ transfers electrons to FMN within complex I. NADH is oxidized to _____(b)_____; FMN is reduced. FMN can accept two electrons from NADH and pass them one at a time to the FeS clusters. If no oxygen is available, the reduced form of electron carriers will accumulate and so will NADH (which will shut down the _____(c)_____)
(a) NADH (b) NAD+ (c) TCA Cycle
200
Fill in the blanks about Complex II of the electron transport chain. FADH2 carries lower energy electrons. FADH2 is a coenzyme with succinate dehydrogenase in the _____(a)_____. Electrons from FADH2 are donated to ubiquinone without a movement of protons across the membrane. From ubiquinone (UQ in this figure), the electrons move to _____(b)_____. No protons are pumped by complex II. For these reasons, complex II is often left out of figures showing the electron transport chain. Oxidation of one FADH2 yields _____(c)_____ protons pumped across the membrane.
(a) TCA Cycle (b) Complex III (c) 6
200
What does F0 provide?
F0 provides the conduit for transport of protons down their electrochemical gradient (from IM space to matrix).
200
Fill in the blanks about ATP synthase. ADP and inorganic phosphate (PO4) bind a/b subunits in the _____(a)_____ conformation. A 120˚ turn causes this site to change into the _____(b)_____ conformation. Another 120˚ turn causes this site to change into the _____(c)_____ conformation that forces phosphoanhydride bond formation. Another 120˚ turn causes this site to revert to the _____(d)_____ conformation. ATP falls out and the cycle can start over.
(a) Open (b) Loose (c) Tight (d) Open
300
True or false? Oxygen cannot diffuse across membranes into the matrix
False, oxygen can diffuse across membranes into the matrix
300
Which complex has 7 or 8 iron-sulfer clusters depending of the species it is from?
Complex I; each one will accept one electron at a time and then pass it on to the next cluster and ultimately to Q.
300
Fill in the blanks about Complex III of the electron transport chain. Complex III contains _____(a)_____ with _____(b)_____ groups that serve as the electron carriers. Transfer of electrons from Q to complex III leads to movement of _____(c)_____ protons across the membrane. Q helps shuttle protons across the membrane as it gives up its two electrons (one at a time). Electrons are transferred from Complex III to _____(d)_____.
(a) cytochromes (b) heme (c) 4 (d) cytochrome c
300
Which subunits of the ATP synthase rotate as protons pass through?
c, y, epsilon
300
Answer the following about ATP synthase. (a) One complete turn of c and y gives how many ATPs? (b) Passage of how many protons through c is thought to be required for one complete turn? (c)One high energy pair of electrons NADH is sufficient to pump how many protons across the inner membrane? How many ATPs can be formed from the oxidation of one NADH?
(a) 3 (b) 12 (c) 100; 12
400
Which complex of the electron transport chain is part of the TCA cycle?
Complex II. Complexes I, III, and IV are the core of the electron transport chain.
400
Fill in the blanks about Coenzyme Q. Electrons move from the FeS clusters to ubiquinone (also called coenzyme Q). Q can accept _____(a)_____ electrons and two protons. Transfer of electrons through complex I to Q induces movement of 4 protons across the membrane. Active transport process - protons are moved uphill, against their electrochemical gradient. Q then shuttles the electrons over to _____(b)_____.
(a) 2 (b) Complex III
400
Fill in the blanks about Complex IV of the electron transport chain. Complex IV reduces oxygen to water. Electrons are passed from Cyt C to complex IV, then on to _____(a)_____. Two H+ are picked up from the environment to make water. _____(b)_____ protons are pumped across the membrane by complex IV per pair of electrons. However, 4 electrons are required in the reaction that reduces one O2 molecule to generate 2 water molecules. Four cytochrome c donate 4 electrons to complex IV. Four protons are consumed from the matrix side (this contributes to the proton-motive force). They combine with two O atoms and 4 electrons to make water. _____(c)_____ H+ are pumped across the membrane for every O2 consumed.
(a) O2 (b) 2 (c) 4
400
True or false? It is thought that binding and subsequent release of 12 protons will give one, 360˚ turn of the the c ring. Rotation of c causes the rotation of the y subunit, which extend all the way through the middle of the a/b subunits of F1
True
400
Fill in the blanks. Movement of substrates and products of respiration across the inner membrane require _____(a)_____. The proton electrochemical gradient helps drive phosphate and pyruvate into the matrix (symport), and also the exchange of ADP for _____(b)_____.
(a) Transporters (b) ATP
500
Fill in the blanks about the electron transport chain. Approximately _____(a)_____ protons are pumped across the inner membrane against the concentration gradient (active transport) as _____(b)_____ electrons are transported from NADH to O2
(a) 10 (b) 2 Protons pump from the matrix to the intermembrane space.
500
We can describe the relative ability of a donor to give up or acquire electrons as its what?
Redox potential; movement of electrons from complex I to Q has a large drop in redox potential (electrons move from a higher energy state to a lower energy state). The energy released is used to pump protons across the membrane.
500
Oxygen can diffuse across membranes into the matrix. What can diffuse out?
Carbon dioxide
500
True or false? Conformational changes of a/b are driven by 360˚ turns of the asymmetrically shaped y subunit
False, 120˚turns
500
Fill in the blanks. In the case of ATP, there is a net displacement of _____(a)_____ negative charge into the intermembrane space. The positive charges from the proton motive force help drive ATP out of the _____(b)_____.
(a) 1 (b) matrix